Rotor and rotor gear assembly for a rotary internal combustion engine

ABSTRACT

A rotor and rotor gear assembly for use in a rotary internal combustion engine of the trochoidal type adapted to absorb deflections of a rotor and a rotor gear due to their different thermal expansions for thereby preventing a connecting pin from being subjected to excessive mechanical stresses. The rotor and rotor gear assembly includes at least three cylindrical bushings which are tightly but rotatably inserted into bore means formed in the rotor gear. Each of the cylindrical bushings is provided with an axially extending eccentric hole into which the connecting pin is disposed to connect the rotor gear to the rotor. The cylindrical bushings are located in the associated bore means formed in the rotor gear in such a manner that the center of each eccentric hole of the cylindrical bushings is angularly displaced with respect to the center line which connects the center of the rotor and the center of the bushing so as to cause the connecting pin to rotate the associated cylindrical bushing when the rotor and rotor gear are subjected to different thermal expansions respectively.

United States Patent 91 Ishikawa 51 Mar. l2, 1974 ROTOR AND ROTOR GEAR ASSEMBLY FOR A ROTARY INTERNAL COMBUSTION [73] Assignee: Nissan Motor Company, Limited,

Yokohama City, Japan 22 Filed: June 30,1972 21 Appl. No.: 268,168

[30] Foreign Application Priority Data July I6, 1971 Japan 46-52867 [52] U.S. Cl 418/61 74/411. 74/431, 85/1 R [51) Int. Cl. F04b 21/00 [58] Field of Search 418/61; 74/41 1, 431, 433; 85/1 R [56] References Cited UNITED STATES PATENTS 3,400,604 9/1968 Jones 418/61 2,702,995 3/1955 Biedess 74/411 3,295,754 1/1967 Abermeth et al..,.. 418/61 3,297,240 1/1967 Tatsutomi 418/61 3,383,936 5/1968 Corwin 74/433 3,655,302 4/1972 Hermes et a1 418/61 Primary Examiner-C. ,l. Husar [5 7] ABSTRACT A rotor and rotor gear assembly for use in a rotary internal combustion engine of the trochoidal type adapted to absorb deflections of a rotor and a rotor gear due to their different thermal expansions for thereby preventing a connecting pin from being subjected to excessive mechanical stresses. The rotor and rotor gear assembly includes at least three cylindrical bushings which are tightly but rotatably inserted into bore means formed in the rotor gear. Each of the cylindrical bushings is provided with an axially extending eccentric hole into which the connecting pin is disposed to connect the rotor gear to the rotor. The cylindrical bushings are located in the associated bore means formed in the rotor gear in such a manner that the center of each eccentric hole of the cylindrical bushings is angularly displaced with respect to the center line which connects the center of the rotor and the center of the bushing so as to cause the connecting pin to rotate the associated cylindricalbushing when the rotor and rotor gear are subjected to different thermal expansions respectively.

2 Claims, 3 Drawing Figures PAIENIEUMAR 12 1914 3.796; 524 sum 1 0r 2 ROTOR AND ROTOR GEAR ASSEMBLY FOR A ROTARY INTERNAL COMBUSTION ENGINE This invention relates to a rotary internal combustion engine of the trochoidal type and, more particularly, to a rotor and rotor gear assembly for use in the rotary internal combustion engine of the type above described.

'The rotary internal combustion engine of the trochoidal type to which the present invention is directed has a rotor which is slidably received within a trochoidal chamber formed in a housing, and a rotor gear which is rotatable with the rotor. The rotor and rotor gear are usually separately formed from each other and both members are usually connected to each other by suitable fastener means such as bolts.

As is well known in the art, the rotor has three apex portions with convexly arcuate working faces extending between adjacent apex portions. A troughlike cutout or recess is provided in each working face and serves as a combustion chamber. As previously described, the rotor is rotatably disposed in the trochoidal chamber of the housing and repeatedly exposed to a high temperature of the burning gases so that the thermal expansion of the rotor becomes greater than that of the rotor gear which is usually formed by forgoing. Thus, a problem is encountered in the prior art rotor and rotor gear assembly in that the connecting portion between the rotor and rotor gear is subjected to unusual mechanical stresses due to the difference in thermal expansion therebetween and accordingly frequent replacement is required. This problem becomes more serious especially where the rotor is made of a lightweight aluminum alloy for increasing the output speed of the rotary internal combustion engine.

The present invention contemplates to eliminate the above-mentioned shortcomings encountered in the prior art rotor and rotor gear assembly and provided an improved rotor and rotor gear assembly for use in a rotary internal combustion engine, which rotor and rotor gear assembly has a connecting. portion adapted to absorb deflections of the rotor and rotor gear due to their different thermal expansions for thereby preventing the rotor and rotor gear from being subjected to unusual mechanical stresses.

According to an important feature of the present invention, the rotor gear is provided with at least three bore means at circumferentially equally divided positions in which bushings are tightly but rotatably inserted. Each of the bushings has an axially extending hole, the center of which is slightly displaced from the center of the bushing per se. These bushings are disposed in the bore means of the rotor gear in such a manner that the centers of respective holes lay on the circular path the radius of which is slightly smaller than that of the circular path on which the centers of the bushings lay. The rotor is provided with at least three pins at circumferentially equally divided positions, which are inserted into the holes of the bushings, re-

spectively.,With' this arrangement, if the rotor is subdescription when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a plan view of a preferred embodiment of the rotor and rotor gear assembly according to the present invention; a

FIG. 2 is a sectional view of the rotor and rotor gear assembly shown in FIG. 1; and 7 FIG. 3 is a schematic view illustrating the function of the rotor and rotor gear assembly implementing the present invention.

Referring now to the drawings and more particularly to FIGS. 1 and 2, there is shown a preferred embodiment of the rotor and rotor gear assembly according to the present invention which is specifically suited for use in a rotary internal combustion engine of the trochoidal type. As shown, the rotor and rotor gear assembly, generally designated at 10, includes a rotor 12 and a rotor gear 14 which is mounted thereon. The rotor 12 is shown as having three apex portions 16, 18 and 20 with convexly arcuate working faces 22, 24 and 26 extending between adjacent apex portions. A trough-like cutout or recess 28 is provided in each arcuate working face. The rotor l2 has an axial bore 30 in which a drive shaft (not shown) provided with a smaller diameter gear than the rotor gear and meshing with the rotor gear is disposed so that the rotor 12 is eccentrically rotatable in the trochoidal chamber of the housing (not shown). This rotor 12 is also provided with an annular recess 32 on one side thereof for a reason to be described in detail.

The rotor gear 14, which is herein shown as being internally toothed, is provided with a plurality of bore means 34, into which cylindrical bushings are rotatably disposed. Each of these cylindrical bushings 36 is provided with an axial hole 38, the center of which is displaced from that of the cylindrical bushing per se in such a manner as will be clearly described hereinafter. This rotor gear 14 is placed in the annular recess 32 formed in the rotor 12 and is secured thereto by connecting pins 40. More specifically, the connecting pins 40 are inserted into the axially extending eccentric holes 38 of the cylindrical bushings 36 and screwed into the rotor 12.

A very important feature of the: present invention is that the cylindrical bushings 36 are tightly but rotatably inserted into the bore means 34 formed in the rotor gear 14 in such a manner that the center of each axially extending eccentric hole of the cylindrical bushings 36 lies on a common circular path the radius of which is slightly smaller than that of the circular path on which the center of the cylindrical bushing 36 lay.

Now assuming that, when the rotor is cold, the center of the bore means 34 and accordingly the center P of the cylindrical bushing 36 lies on a circular path the radius of which is represented by R whereas the center of the axially extending eccentric hole 38 and accordingly the center Q of the connecting pin 40 lies on a circular path the radius of curvature of which is represented by R (see the righbhand portion of FIG. 3), the

connecting pin 40 rotates about the center point P of the cylindrical bushing 36 to assume a position shown in left-hand portion of FIG. 3 where the center Q of the connecting pin 40 lies on a circular path the radius of which is represented by R when the rotor is thermally expanded. Thus, it will be seen that when the rotor is subjected to thermal expansion, the connecting pin 40 turns about the center point Pthereby rotating the cylindrical bushing 36.

Referring now to FIG. 3, the right side portion illustrates the relative positions of one of the bushings 36 and its corresponding connecting pin 40 when the rotor (not shown in FIG. 3) is cold. As shown, the center point P of the bushing 36 lies on a circle having a radius R OP where O is the center point of the rotor and the rotor gear whilst the center point Q of the connecting pin 40 lies on a circle having a radius R Q. It is another important feature of this invention that the relative sizes of the bushing 36 and the connecting pin 40 are selected in such a manner that the points R0 and Q form a small angle POQ so that when the rotor is subjected to thermal expansion the connecting pin turns the bushing to the position shown in the left side portion of FIG. 3. Here the center point of the connecting pin lies on a circle having a radius R; OQ the points P, O and 0 still forming a relatively small angle POQ. As described hereinbefore, the rotation of the bushing 36 by the connecting pin accommodates the thermal expansion of the rotor without causing undue stresses on the connecting pin 40.

It will be appreciated that it is possible to maintain venting the pins 40 from being subjected to unusual mechanical stresses. v

What is claimed is:

l. A rotor and rotor gear assembly for use in a rotary internal combustion engine of the trochoidal type, comprising, in combination, a rotor having an annular recess formed on one side thereof, a rotor gear having at least three bore means, cylindrical bushings tightly but rotatably inserted into said bore means of said rotor gear, said cylindrical bushings having axially extending eccentric holes respectively, and.connecting pins disposed in said axially extending eccentric holes and connected to said rotor for mounting said rotor gear thereon, the center of each axially extending eccentric hole of said cylindrical bushings being angularly displaced with respect to the center line which connects the center of said rotor and the center of each cylindrical bushing, whereby, when said rotor is subjected to thermal expansion, said connecting pins rotate said cylindrical bushings about the centers of said cylindrical bushing respectively to absorb deflections of said rotor and rotor gear due to their different thermal expansions for thereby preventing said connecting pins from being subjected to excessive mechanical stresses.

2. A rotor and rotor gear assembly according to claim 1, wherein the center of each axially extending eccentric hole of said cylindrical bushings lying, when said rotor is cold, on a common circular path the radius of which is slightly smaller that that of the circular path on which the center of each cylindrical bushing liesv 

1. A rotor and rotor gear assembly for use in a rotary internal combustion engine of the trochoidal type, comprising, in combination, a rotor having an annular recess formed on one side thereof, a rotor gear having at least three bore means, cylindrical bushings tightly but rotatably inserted into said bore means of said rotor gear, said cylindrical bushings having axially extending eccentric holes respectively, and connecting pins disposed in said axially extending eccentric holes and connected to said rotor for mounting said rotor gear thereon, the center of each axially extending eccentric hole of said cylindrical bushings being angularly displaced with respect to the center line which connects the center of said rotor and the center of each cylindrical bushing, whereby, when said rotor is subjected to thermal expansion, said connecting pins rotate said cylindrical bushings about the centers of said cylindrical bushing respectively to absorb deflections of said rotor and rotor gear due to their different thermal expansions for thereby preventing said connecting pins from being subjected to excessive mechanical stresses.
 2. A rotor and rotor gear assembly according to claim 1, wherein the center of each axially extending eccentric hole of said cylindrical bushings lying, when said rotor is cold, on a common circular path the radius of which is slightly smaller that that of the circular path on which the center of each cylindrical bushing lies. 